Ocular thromboembolic and ischemic disorders collectively constitute the major cause of blindness in middle-aged and older persons, and yet our knowledge of their etiology, pathogenesis and management is far from satisfactory. One of the major factors in this ignorance is the lack of a suitable experimental animal model duplicating the findings in man. Also, there is little doubt that in modern society hypertension and atherosclerosis constitute major public health problems; both disorders individually or by their combined effect not only are the major source of chronic ill health and premature death but also constitute one of the major causes of visual loss due to ocular vascular occlusive disease. The first goal of this study has been to produce in rhesus monkeys background ocular vascular and systemic cardiovascular changes, resembling those seen in the vast majority of patients with ocular vascular occlusive disorders, i.e., atherosclerosis, arteriosclerosis, arterial hypertension and high serum lipids. This has been done for over 10 years now by feeding them a special atherogenic diet. In a proportion of these animals, over the past several years experimental chronic arterial hypertension has been produced by Goldblatt's procedure The animals are being investigated serially by a detailed ocular examination (including ophthalmoscopy, color fundus photography, and fluorescein fundus angiography) as well as systemic evaluation (by recording blood pressure, and by biochemical and hematologic studies). The long-term objective is to study the pathogenesis, management and other aspects of ocular vascular occlusive disorders and of glaucoma by experimentally producing various types of ocular vascular occlusive lesions (occlusion of central or branch retinal veins, of central retinal artery, and of main or short posterior ciliary arteries) and of glaucoma, in these animals with atherosclerosis, arteriosclerosis, hypertension and high serum lipids. These animals will be followed for periods varying from days to years. The eyes will be investigated serially by a detailed ocular examination, including slit lamp examination, intraocular pressure measurements fundus evaluation (by ophthalmoscopy, color fundus photography and fluorescein fundus angiography), and at termination by detailed pathologic studies (including light and electron microscopy and, where appropriate, autoradiography and/or horseradish peroxidase tracer studies). Information provided by these studies should help in a better understanding of these controversial and illunderstood subjects.